亚硝酸钾，化学式KNO₂。

白色至微黄色棱柱状或棒状易潮解结晶。易溶于水和液氨，微溶于乙醇，不溶于丙酮。水溶液呈碱性。常温下性质稳定。加热至350 °C以上时分解生成氧化钾并放出氧化氮气体。为还原剂，与有机物或其他可燃物接触可引起燃烧和爆炸，与铵盐或氰化物相混合时可能发生爆炸。遇酸放出剧毒的氧化氮气体。有毒，致癌。毒理见亚硝酸盐中毒。

Potassium nitrite (distinct from potassium nitrate) is the inorganic compound with the chemical formula KNO₂. It is an ionic salt of potassium ions K and nitrite ions NO₂, which forms a white or slightly yellow, hygroscopic crystalline powder that is soluble in water.